The growth and development of plants mainly relies on sunlight. In some instances, e.g., commercial crops, such as vegetables, flowers and medicinal plants, their industrialization and tissue culture relies upon artificial light. This can especially be the case when the light application time is very short, or in seasons that include weather having continuous cloudy days, rain filled days and/or snow days. Artificial lighting, as a direct light supply inside greenhouses, is an efficient way to promote the growth of plants. The theoretical basis on efficient and energy-saving supplementary light for plants is mainly from the theory that plants will absorb the light selectively. LED light sources can be used as artificial lighting inside greenhouses so as to enhance growth and quality of plants. Compared with traditional artificial lighting, features of LEDs include adjustable light intensity, light spectrum, low cooling load, high electro-optic conversion efficiency, small volume, long service life, using direct current and setting of special wavelength, fixing of wavelength etc, without harmful gas or with good performance on environmental protection, and thus LED is an artificial lighting system quite suitable for tissue culture of plants.